Connector



Oct. 25, 1949. slLLlMAN 2,485,930

CONNECTOR Filed Sept. 6, 1945 INVENTOR.

ROBERT M. SILUMAN '%M2- A444 ATTORNEY.

Patented Oct. 25, 1949 CONNECTOR Robert Silliman; Silver Spring, .Md., mignor to: the Uniterl States of Amenioa-as representedv by the Secretary of-War Application September 6, Maseru-No; 6145732 4 Claims. (01. 173-324) This invention: relates; to? radio receiversand transmitters.

More specifically; it relates tomeans:- for com necting a radio frequency receiver or: transmitter througha transmission line to its associated antenna It is of particular use inconnection with apparatus installed: on aircraft. which: is designed to operate: over a wide range of high frequencies.

Heretofore, connections from transmission iines to antennas have been.accompiishedfbywire conductors of relatively small cross section with relation to the crosse-scction of thes radiatingzsun face of the" antenna. Such conventional arranga ments will feed radio froquency energy into the antenna in the case of a transmittercor'convey it from'the antenna to the= receiver in the case of a receiver in a satisfactbrymanncrat relatively low radio frequencies; iiowever whenltheioper ating frequencies are such'that theircorresponw ing wavelengthsapprcach the same:orderfcfai magnitude asthe' dimensions of the circuit elements and their connections, wire conductors: present abrupt changes in the dimensions Y of: the system and cause serious electrical discontinuities because of the large' differences: inthe characteristic impedances of the associated elements. This results in an inoreased standing wave ratio on I the transmission linowto the antennaand a'rcsulta ing serious decreasein 'energy'transfer.

'It is an Qbjectof the present invention tornrm vide meansfor electrically connecting'the ttansmission line of a receiver-1 or transmitter to its antenna by which electrical discontinuity is: do creased and the standing wave ratio is greatly improved. 7

Another object of this invention is to provide a connection between an antenna and its associated apparatusin which current density along the connection and at the-place whorethe current is introduced to. the radiating; surface of the. an! tenna' is substantially uniform;

It is a further object otthis inventionto provide means for efficiently transferring energy to or from an antenna over a wider range of operating frequencies than has been possible with devices of the'prior art.

Other: objects, features,- and advantages of this invention will suggest themselves to those' skilled in the art and will become apparent from the following description takenirt connection with the accompanying drawings in which:-

Fig 1 is a lan view or swank-from which a device embodying the principles of the present invention-might bezmado;

Fig; 2"is aside elevation oil a-aconnector embodyingthe present invention;

Fig; 3 is? a. front: clevational: viewshowing the connection of adevice embodying: the present invention "to a stub antenna Figr iwisa side elevation of-Fig.- 3;

Fig. 5 isan isometric view of a device-embody ing the presentinventlon'connecting an antenna mounted on anairplane to atransmission" line andthe associated supporting structure;- and Figsl 6! and GA respectively are diagrammatic representations" showing current distribution in devices rof the prior art andina-device employing the presentinventiom A connector l0 employing"theprincipleof the present inventionisingeneralofan isoaceles'trap ezoidal shapeas shown in Fig. 1-. The dimensions of the connector are dependent upon the'sizeof the antenna. and transmission line used. Thus the-large end H- of theconnecton is'of suflicient length toextend over acfair proportion-oftheside of a-fiat antenna-or over a littleless thana semiacircle of an antenna otncircular cross-sectionl Thesmaller end I2 is'designed-to fitaround the circumference at the inner. conductor of atransmission line. Preferably the connectorv should be of'equalthickness throughout.

The connector may be made. of any. current carrying material but for best resultsit shouldlbe of the same material as the el'ement forming the radiating. surface" of the antenna. in order to eliminateany. electrical discontinuity due to the use or metals having'difierentcontact potentials.

Adjacent to the'larger end I l, asshown in vFig. 2', a: portion it of the connector is bent to conform to the'shape of the antenna with which it is to be used. At thenarrow and I2, asshown in Fig. 2, a portion M is bent to'el'icircle the end of the inner conductor of-the transmission line. It of great importance that the shape into which the connct'oris' bent alongitslongitudinal axis, as generally shcwn at 15; Fig. 2, be a smooth curve having no abrupt changes in direction, kinks, or bumps. However, the-exact form of the curve into whicn-theconnector is formed is tosome extent dependent upon the shape, size, and position" of neighboring metallic surfaces which may react onthoradid frequency-fields which are present.

The length of the connector along its longdv tudihal aids-shouldbe a small 'iraction'of the wave length corresponding to the highest operating frequency; preferably not over one-eighth of a wavelength.

In Figs 3' and 4 theattachment of'theconnec tor M to e-flat stubantennal6; constructedora wooden core I! surrounded by a metallic element l8 forming the radiating surface, is shown. Portion I3 of the connector is welded to the radiating surface [8 of the antenna. Preferably this is close to base 19 of the radiating surface but should be sufllciently far above the base to provide a large surface of contact between the radiating surface and the connector. The connector, as previously stated, is bent along a smooth curve for the portion I 5, terminating in the portion 64 attaching it to the inner conductor of transmission line 20.

The connector is, for its entir length, symmetrical about its longitudinal axis. 'Any devia-' tion from symmetry, especially in proximity to the radiating element of the antenna will tend,

how an antenna connector employing the principles of the present invention attains a gradual due to capacity efiects, to disturb the electric balance of the whole connection and to cause a 7 discontinuity in impedance.

It may be seen from the above description that neither the connector, its attachment to the transmission line, nor to the antenna presents any serious electrical discontinuity. The tapered Shape of connector H) provides, for its entire length, a gradual change in dimension resulting in a gradual change in electrical characteristics and a gradual change in distribution of the cur- .rent carried by it to or from the antenna. No

discontinuity occurs at the connection to the transmission line because there is there provided a large area of contact, a small change in crosssection of the current carrying member, and no abrupt change in direction. Similarly, electrical continuity is preserved at the attachment to the antenna by reason of the large contact area, of the gradual curve away from the radiating surface, and of the symmetrical position of the connector.

The detailed arrangement of one embodiment of the invention applied to apparatus mounted on aircraft is shown in Fig. 5. The antenna [6 is mounted so that all of the radiating surface I8 is outside of the metallic fuselage 2|. The wooden core I! of the antenna extends into the aircraft and is supported by a structure designed for that purpose and generally designated as 22'. Structure 22 consists of two lateral metallic supporting plates 23 and 24 an intermediate wooden transverse support 25 and an end wooden transverse support 26. The lateral plates 23 and 24 are attached to fuselage 2| and the transverse supports are attached to the lateral plates by any suitable means. Transmission line is supported by a plate 21 of any suitable type and passes through transverse support to the point where its inner conductor is connected to connector ID as above described. If desired transmission line 20 may be brought out through one of the lateral plates through an aperture 28, as shown in plate 24, provided for that purpose.

An opening in the fuselage fitted with an insulating grommet 29, preferably of soft rubber to provid a cushioning effect, is provided through which antenna l6 passes. The antenna is held firmly in position by transverse supports 25 and 2B.

Connector I0 is attached in the manner above described to the antennaat the base of the radiating surface H! which terminates a short distance outside of the fuselage 2!. The shape into which connector I0 is bent,-as above stated,

must be free from abrupt changes in direction,

kinks, or bumps but its exact shape is determined by the size, shape, and proximity of neighboring change in current distribution from transmission line to antenna. If connection, as in the prior art, were made by wire, the pattern of current distribution, as shown in Fig. 6, would be very dense through connector l0, then would spread suddenly when reaching the much larger conducting area of the antenna. This sudden spread, as is shown at 30, results in an uneven distribution of current over the radiating surface I8. In a connector employing the principles of the present invention, the current as shown in Fig. 6A passes from transmission line 20 through portion l4, portion I5and the connection to the antenna at I3. Since both the inductance and resistance of connector l0 steadily decrease in proportion to its increase in width, the current, steadily spreads out over the entire width as it travels along portion l5 and into the radiating element of the antenna. There is no abrupt change of area at the antenna so the gradual spreading out of the current continues. The result is that the current distribution in the antenna, as shown at 3| in Fig. 6A, is uniform over the width of the radiating element.

The above descriptions of specific embodiments of the invention and discussion of the electrical and mechanical principles affecting its operation will instruct one skilled in the art how to make and attach connectors employing the present in vention for varying conditions encountered and for various operating characteristics required. Thus having before one fixed electrical conditions and mechanical arrangement of antenna and supporting structure, by the application of the principles herein disclosed, a connector may be designed to present a minimum of electrical discontinuity between transmission line and to provide even current distribution in the antenna resulting in optimum energy transfer.

While there has been here described what is at present considered to be the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modie fications may be made therein without departing from the scope of the invention.

What is claimed is:

1. In a radio signaling apparatus including an antenna, a supporting structure therefor and a metallic conductor for supplying high frequency energy to said antenna; an electrical connector comprising a sheet of conductive material having greater width at one end than at the other and symmetrical about a longitudinal axis, said sheet having said wider end and a substantial area adjacent thereto formed into a substantially cylindrical shape having dimensions substantially equal to the outer dimensions of said antenna, said cylindrically formed portion flowing smoothly and gradually'into a section of said connector intermediate the ends thereof, said intermediate section being substantially flat in a direction perpendicular to said longitudinal axis but curved in a direction along said axis,- said. sheet also being provided with a second cylindrically formed portion adjacent its narrow end, said second cylin drically formed portion having inner dimensions substantially equal to the outer dimensions of said conductor, said second formed portion flow" ing smoothly and gradually to the shape of said intermediate portion, and means for joining said first and second formed end portions of said connector respectively to said antenna and said conductor whereby electrical energy flowing between said conductor and said antenna encounters no abrupt changes in cross section of said connector.

2. A connector for joining two circular conductors of different diameters in non-coaxial alignment, comprising a sheet of conductive material a of greater size at one end than at the other and symmetrical about a longitudinal axis, said sheet having the end of greater size and a substantial area adjacent thereto formed in the shape of a cylinder having an inner diameter equal to the outer diameter of the larger of said two conductors, said sheet having the narrower end thereof and a substantial area adjacent thereto formed in the shape of a cylinder having an inner diameter equal to the outer diameter of the smaller of said two conductors, said sheet having a substantially fiat portion intermediate the ends thereof, the areas between said fiat portion and said formed end portions being curved so as to provide a smooth transition between said portions, and means for connecting said formed end portions to said conductors respectively whereby high frequency electrical energy flowing between said two conductors encounters no abrupt change in electrical impedance.

3. An electrical connector for joining two conductors having incongruent cross sections and unaligned axes, comprising a sheet of conductive material symmetrical about an axis, said sheet having first and second ends thereof and subi for joining one of said conductors to each end of said connector, whereby a continuous electrical path for high frequency currents is afforded between the surfaces of said conductors that is free from abrupt changes in shape or electrical impedance.

4. A connector for high frequency currents for connecting a cylindrical terminal of an antenna to a circular inner conductor of a coaxial line, said inner conductor being of smaller diameter than said terminal, comprising a sheet of conducting material having substantially constant thickness throughout but being of tapering crosssectional area so as to have a large end and a small end, said large end having the configuration of a portion of a cylindrical surface of a size to extend at least partly about said terminal and be secured thereto, said small end having the configuration of a portion of a cylindrical surface of a size to extend at least partly about said inner conductor and be secured thereto, the portion of said connector intermediate said ends being shaped to curve smoothly into said ends, whereby said conductor forms a high frequency path between said terminal and said inner conductor which is substantially free from electrical discontinuities and in which the variations in current density and impedance are substantially uniform.

ROBERT M. SILLIMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,018,320 Van B. Roberts Oct. 22, 1935 2,058,787 Greger Oct. 27, 1936 2,115,826 Norton et a1. May 3, 1938 2,239,724 Lindenblad Apr. 29, 1941 2,267,268 Burrows Dec. 23, 1941 FOREIGN PATENTS Number Country Date 311,492 Germany July 14, 1917 

